Method for manufacturing a liquid discharge head, liquid discharge head, and liquid discharge device

Abstract

This prevents adhesive from overflowing into the openings provided on the substrate of the liquid dispensing head. [Solution] One embodiment of the present disclosure is a method for manufacturing a liquid discharge head, characterized in that, with respect to the width of the recess in the X direction and the width of the recess in the Y direction, H is the distance between the first substrate and the second substrate in the Z direction, P1 is the pressure generated on the liquid surface as the end face of the adhesive in contact with the flow channel within the bonded region when the adhesive does not protrude from the bonded region, P2 is the pressure generated on the liquid surface as the end face of the adhesive in contact with the flow channel within the range of 1.0H ≤ L ≤ 1.5H when the adhesive protrudes from the bonded region, and P3 is the pressure generated on the liquid surface of the adhesive in the recess, such that P1 ≥ P3 ≥ P2.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a liquid ejection head, a liquid ejection head, and a liquid ejection device.

Background Art

[0002] In recent years, in the manufacture of functional devices such as MEMS (Micro Electro Mechanical Systems) such as pressure sensors and acceleration sensors and microfluidic devices, devices composed of a substrate assembly in which substrates are joined to each other via an adhesive have been created. As an example thereof, a liquid ejection head that ejects liquid can be mentioned. As an example of a liquid ejection head, an inkjet recording head can be mentioned.

[0003] Such an inkjet recording head has an energy generating element that generates energy for ejecting ink. Further, a discharge port member is formed on the substrate surface, and a plurality of discharge ports (also referred to as nozzles) for ejecting ink are arranged in the discharge port member. Further, through holes serving as ink flow paths are formed in the substrate, and ink is supplied from the back surface side to the front surface side of the substrate through the through holes. The through holes and the discharge ports are in communication with each other, and the ink that has passed through the through holes is ejected from the discharge ports by the force applied from the energy generating element. Examples of the energy generating element include an element that boils ink by energization heating such as a heater element, and an element that applies pressure to a liquid by utilizing a volume change such as a piezoelectric element.

[0004] Patent Document 1 discloses, as an example of a device composed of a substrate assembly, a liquid ejection device. Specifically, the head of the liquid ejection device has a pressure generation chamber communicating with a nozzle opening and a piezoelectric element provided with an electrode provided in a piezoelectric layer, and the liquid stored in the pressure generation chamber is ejected through the nozzle opening. Generally, in a liquid ejection device such as that of Patent Document 1, a plurality of substrates are joined using an adhesive.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-320171 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, when joining these substrates, the adhesive may seep out onto structures formed on the substrate surface being joined. This excess adhesive can affect the ejection characteristics. For example, if a large amount of adhesive seeps into an opening that houses an energy generating element such as a piezoelectric element, it can affect the operation. In particular, if the opening that serves as the ink channel is small, blockage by the adhesive is more likely to occur, leading to problems such as the inability to eject ink.

[0007] To address this adhesive overflow, one possible solution is to create recesses in the opening patterns to contain excess adhesive. For example, recesses capable of containing adhesive could be placed around openings housing energy generating elements or ink channels to prevent the adhesive from flowing into the openings. However, simply placing large recesses to block the adhesive sometimes fails to sufficiently suppress the occurrence of problems.

[0008] Therefore, in view of the above problems, this disclosure aims to accurately control the overflow of adhesive into an opening provided in the substrate of a liquid dispensing head. [Means for solving the problem]

[0009] One embodiment of the present disclosure is a method for manufacturing a liquid discharge head in which a first substrate and a second substrate are joined via an adhesive, comprising the steps of: preparing a first substrate and a second substrate, each having a first opening that serves as a liquid flow path and a recess that accommodates a portion of the adhesive formed in at least one of them; joining the first substrate and the second substrate via an adhesive to form a bonding region between the first substrate and the second substrate; and curing the adhesive, wherein the width of the recess in the short direction of the first substrate and the width of the recess in the longitudinal direction of the first substrate are determined in the stacking direction of the first substrate and the second substrate. A method for manufacturing a liquid discharge head, characterized in that, after the step of forming the bonding region and before the curing step, when the adhesive does not protrude from the bonding region, P1 is the pressure generated on the liquid surface as the end face of the adhesive in contact with the flow path within the bonding region, and when the adhesive does protrude from the bonding region, P2 is the pressure generated on the liquid surface as the end face of the adhesive in contact with the flow path within the range of 1.0H ≤ L ≤ 1.5H, where L is the length of the protruding adhesive, and P3 is the pressure generated on the liquid surface of the adhesive in the recess, such that P1 ≥ P3 ≥ P2. [Effects of the Invention]

[0010] According to this disclosure, it is possible to precisely control the overflow of adhesive into an opening provided in the substrate of the liquid dispensing head. [Brief explanation of the drawing]

[0011] [Figure 1] Diagram showing the configuration of the recording device in the first embodiment. [Figure 2] schematic cross-sectional view of the bonded substrate in the first embodiment [Figure 3] Diagram illustrating the pressure P1 generated at the liquid surface of the adhesive at the edge of the substrate. [Figure 4] Diagram illustrating the pressure P2 generated at the liquid surface of the adhesive that has spilled out from the edge of the substrate. [Figure 5] Explanatory drawing of the pressure P3 generated at the liquid surface of the adhesive in the recess [Figure 6] Schematic cross-sectional view in the first embodiment [Figure 7] Schematic cross-sectional view in the first embodiment [Figure 8] Schematic cross-sectional view in the first embodiment [Figure 9] Schematic cross-sectional view in the first embodiment [Figure 10] Drawing showing the drawing-in of the adhesive from the end of the substrate [Figure 11] Schematic cross-sectional view showing the pressure range in the first embodiment [Figure 12] Schematic cross-sectional view showing the pressure range in the first embodiment [Figure 13] Schematic cross-sectional view showing the pressure range in the first embodiment [Figure 14] Drawing showing the capillary rise due to the recess in the first embodiment [Figure 15] Drawing showing the capillary rise due to the recess in the first embodiment [Figure 16] Schematic plan view of the bonded substrate [Figure 17] Schematic cross-sectional view showing the manufacturing method of the bonded substrate in the first embodiment [Figure 18] Schematic cross-sectional view showing the manufacturing method of the bonded substrate in the first embodiment [Figure 19] Schematic cross-sectional view showing the manufacturing method of the bonded substrate in the first embodiment [Figure 20] Liquid discharge device having a liquid discharge head manufactured using the bonded substrate [Figure 21] Schematic cross-sectional view showing the behavior of the adhesive in the recess in the first embodiment [Figure 22] Schematic plan view of the planar shape of the recess in the first embodiment<0​​​​​​​​ [Figure 26] Schematic diagram of the planar shape of the recess in the first embodiment [Figure 27] Schematic diagram of the planar shape of the recess in the first embodiment [Figure 28] Schematic diagram of the planar shape of the recess in the first embodiment [Figure 29] Schematic diagram of the planar shape of the recess in the first embodiment [Modes for carrying out the invention]

[0012] Preferred embodiments of this disclosure will be described below with reference to the drawings. While specific descriptions may be given in the embodiments described below to fully illustrate this disclosure, these are merely technically preferred examples and are not intended to unnecessarily limit the scope of this disclosure. For example, the dimensions, materials, shapes, and relative arrangements of the components described in the embodiments below are not intended to limit the scope of this disclosure unless otherwise specified. Furthermore, while the embodiments below describe the joining of two or three substrates as an example, this disclosure is not limited thereto, and the technology of this disclosure can be applied to joining multiple substrates.

[0013] Furthermore, unless otherwise specified, the materials, shapes, etc., of the components described in the following explanation will be the same as those described in the initial explanation.

[0014] [First Embodiment] The substrate for the liquid discharge head in this embodiment will be described below.

[0015] <Recording device configuration> A liquid ejection head is a component of a recording device such as an inkjet printer. In addition to the liquid ejection head, such a recording device is also equipped with a liquid storage section for storing the liquid supplied to the liquid ejection head, a transport mechanism for transporting the recording medium on which images are recorded, and so on.

[0016] Figure 1(a) is a schematic diagram showing a recording device 100, which is an example of a liquid ejection device in this embodiment. The recording device 100 has a one-pass type liquid ejection head module 101 (hereinafter referred to as the liquid ejection head) that moves the recording medium 102 in one go and records an image on the recording medium 102. The liquid ejection head 101 has ejection ports (also called nozzles) arranged over a length corresponding to the entire width of the recording medium 102. The liquid ejection head 101 in this embodiment is a head corresponding to four colors: cyan (C), magenta (M), yellow (Y), and black (K), which are shown as Ka, Kb, Ya, Yb, Ma, Mb, Ca, and Cb in Figure 1(a), respectively. Thus, the recording device 100 is provided with two liquid ejection heads for the same ink color. The recording medium 102 is transported in the direction of arrow A by the transport unit 103, and image recording with ink ejection is performed on the transported recording medium 102 by the liquid ejection head 101. Note that the recording device 100 shown in Figure 1(a) is merely an example, and it may be configured to accommodate any type of liquid discharge head. For example, the recording device 100 may have only one type of liquid discharge head, or it may have more than four types of liquid discharge heads.

[0017] The coordinate axes are defined as shown in Figure 1(a). Specifically, the width direction of the recording medium is the Y direction, the direction of gravity (also called the height direction) is the Z direction, and the direction perpendicular to both the Y and Z directions is the X direction. The direction of arrow A, which carries the recording medium 102, is the -X direction. These coordinate axes are applied similarly to other drawings as needed. With respect to these coordinate axes, as shown in Figures 1(b) and 1(c), the X direction is the short side of the substrate, the Y direction is the long side of the substrate, and as shown in Figures 2 and later, the Z direction is the stacking direction of the substrate. However, the X direction may be the long side of the substrate and the Y direction may be the short side of the substrate.

[0018] <Configuration of the liquid dispensing head> Figure 1(b) is a diagram illustrating the liquid ejection head 101 in this embodiment, and is a perspective view of one liquid ejection head of any one color from the plurality of liquid ejection heads shown in Figure 1(a). As shown in Figure 1(b), the liquid ejection head 101 has a head body 104. Multiple liquid ejection substrates, each formed including a bonding substrate 80, are arranged on the head body 104, and in the example of Figure 1(b), four liquid ejection substrates are arranged. Each liquid ejection substrate is provided with multiple ejection ports 13 (see Figure 1(c)). The ink ejected from the liquid ejection head is supplied from an ink tank (not shown) to the liquid ejection substrates via a common supply port (not shown) of the head body 104. As shown in Figure 1(b), the four liquid ejection substrates are arranged along the Y direction, and the two liquid ejection substrates that are closest to each other in the Y direction are arranged so that their positions in the X direction are different. As a result, the Y-direction positions of some of the discharge ports 13 (at the Y-direction end) of a certain liquid discharge substrate (first liquid discharge substrate) and some of the discharge ports 13 (at the Y-direction end) of the liquid discharge substrate (second liquid discharge substrate) that is closest to the first liquid discharge substrate in the Y-direction are the same. By arranging multiple liquid discharge substrates in this way, it is possible to achieve recording using a long row of discharge ports.

[0019] Figure 1(c) is a plan view of the liquid discharge substrate as seen from the discharge port 13 surface.

[0020] Figure 2 is a schematic cross-sectional view of the bonding substrate 80 along the cross-sectional line II-II' shown in Figure 1(c). Note that Figure 2 is a schematic view of the area of ​​one discharge port, and the effect of adhesive flowing into the opening is not shown. In this specification, the opening is also referred to as the opening.

[0021] The bonded substrate 80 comprises a first substrate 1, a second substrate 2, and a third substrate 3. The first substrate 1 and the second substrate 2 are bonded together with adhesive 6, and the second substrate 2 and the third substrate 3 are bonded together with adhesive 6. Thus, the bonded substrate of this embodiment has at least one bonding surface formed by adhesive (in the example in Figure 2, the bonded substrate 80 has two bonding surfaces).

[0022] The first substrate 1 is made of, for example, a silicon substrate and has a structure in which a piezoelectric element 9 is formed on a vibrating membrane 11. The second substrate 2 has openings formed to form pressure chambers 12. The vibrating membrane 11 forms the top wall of the pressure chambers 12 and partitions multiple pressure chambers 12. Furthermore, the first substrate 1 has a first opening 7, a second opening 8, and the like formed therein for supplying liquid to the pressure chambers 12.

[0023] The upper part of the bonded substrate 80 is formed by joining the first substrate 1 and the second substrate 2 via an adhesive 6. Here, the first substrate 1 has a first opening 7 and a second opening 8, and the second substrate 2 has a pressure chamber 12. Piezoelectric elements 9 are housed within the second opening 8, corresponding to each of the multiple pressure chambers 12. As shown in the figure, the X-direction position of the end face in contact with the ink flow path on the first substrate 1 is different from the X-direction position of the end face in contact with the ink flow path on the second substrate 2.

[0024] The third substrate 3 is made of, for example, a silicon substrate and has a discharge port 13 for discharging liquid. The discharge port 13 communicates with the pressure chamber 12 and also penetrates the third substrate 3, so when a change in the volume of the pressure chamber 12 occurs, the liquid accumulated in the pressure chamber 12 is discharged from the discharge port 13.

[0025] The first substrate 1 has a first recess 4 and a second recess 5 formed therein. An ink tank (not shown) is placed on the first substrate 1. A first opening 7 is formed so as to penetrate the first substrate 1 and the second substrate 2 and communicate with the pressure chamber 12. Therefore, the liquid in the ink tank is supplied to the pressure chamber 12 through the first opening 7.

[0026] A piezoelectric actuator is constructed by arranging a piezoelectric element 9 on a vibrating membrane 11. This piezoelectric actuator comprises a lower electrode (not shown) formed on a vibrating membrane forming layer, a piezoelectric element 9 formed on the lower electrode, and an upper electrode (not shown) formed on the piezoelectric element 9.

[0027] The vibrating film-forming layer is formed, for example, by plasma CVD. Next, a hydrogen barrier film (not shown), a lower electrode (not shown), a piezoelectric film, and an upper electrode (not shown) are formed in order. The lower and upper electrodes are formed, for example, by sputtering, and the piezoelectric film is formed by the sol-gel method, but may also be formed by sputtering.

[0028] As the piezoelectric element 9, for example, a PZT (lead zirconate titanate) film formed by the sol-gel method or sputtering method can be used. Such a piezoelectric element 9 consists of a sintered body of a metal oxide crystal. An actuator substrate can be formed by forming interlayer films and wiring 10 so that the actuator part can be driven. The wiring 10 is connected to the piezoelectric actuator.

[0029] The piezoelectric element 9 is formed in a position opposite the pressure chamber 12, with the vibrating membrane 11 in between. That is, the piezoelectric element 9 is formed so as to be in contact with the surface of the vibrating membrane 11 opposite to the pressure chamber 12. The vibrating membrane 11 has the characteristic of being deformable in the direction opposite to the pressure chamber 12. When a driving voltage is applied to the piezoelectric element 9 from the driving IC (not shown) via the wiring 10, the piezoelectric element 9 deforms due to the inverse piezoelectric effect. As a result, the vibrating membrane 11 deforms together with the piezoelectric element 9. This causes a change in the volume of the pressure chamber 12, and the liquid is pressurized. The pressurized liquid is discharged from the discharge port 13 as tiny droplets.

[0030] The openings and recesses in this embodiment will now be described. When the second substrate 2 is joined to the first substrate 1 via adhesive 6, the adhesive may block the first opening 7, which serves as an ink channel formed on the joining surface, or protrude into the second opening 8, which houses the piezoelectric element 9, thereby negatively affecting liquid ejection.

[0031] In particular, variations in the application and transfer of the adhesive 6 to the first substrate 1 become noticeable when a sufficient amount of adhesive is needed to fill the step created by the wiring 10 arranged on the joint surface, or when the length of the joint surface between the first substrate 1 and the second substrate 2 is long and a large amount of adhesive 6 is required.

[0032] The inventors of this invention have found that by controlling the size of the recesses within the joining region of these openings to an appropriate range, and by curing the adhesive after it reaches an equilibrium state at the temperature in which the adhesive flows, the size of the adhesive overflow can be controlled to stay within a certain range. Here, equilibrium refers to a state in which the pressure generated by the movement of the adhesive and the resulting liquid surface shape in this embodiment is maintained within a predetermined range.

[0033] The pressure generated at the edges of the adhesive liquid surface in this embodiment will be described below. Note that the adhesive liquid surface shape on the substrate in this embodiment is small enough that the effect of gravity can be ignored, so the effect of gravity will not be considered here. Furthermore, the shape of the edges of the adhesive liquid surface refers to the liquid surface shape formed by the adhesive at the edge of the first substrate 1, specifically at the edge of the first opening 7.

[0034] First, the details of the calculation of the balance between the pressure P1 generated on the liquid surface formed at the end face of the adhesive within the bonding region between the first substrate 1 and the second substrate 2, and the surface tension, will be explained using Figure 3. The bonding region refers to the area of ​​adhesive extending in the XY direction between the first substrate 1 and the second substrate 2, and also has a length in the Z direction. The bonding region is almost synonymous with the bonding surface mentioned above, but in particular it refers to the area contained within the XY plane of the first substrate 1. Pressure P1 refers to the pressure generated on the liquid surface as the end face of the adhesive in contact with the flow path within the bonding region when the adhesive is contained within the bonding region between the first substrate 1 and the second substrate 2, after the process of forming the bonding region and before the process of curing the adhesive. Here, "contained adhesive" means that the adhesive does not spill out of the bonding region.

[0035] If the surface tension of the adhesive is γ, this surface tension γ acts on the first substrate 1 and the second substrate 2 at contact angles θ1 and θ2, respectively. The surface tension at the contact line is given by equation (1). TIFF2026076950000002.tif6150

[0036] In this specification, "contact line" means the length (perimeter) of the one-dimensional region on which the force acts.

[0037] In contrast, the resultant force P1 of the pressure generated on the liquid surface formed at the end face of the adhesive is defined by equation (2), where H is the distance (Z-direction distance) of the bonding surface at the end face of the adhesive between the first substrate 1 and the second substrate 2, and the length of the liquid surface in the Z direction is approximately equal to H. TIFF2026076950000003.tif6150

[0038] The value calculated by equation (1) is equal to the value calculated by equation (2). Therefore, the pressure P1 generated at the end face of the adhesive within the bonding region between the first substrate 1 and the second substrate 2 is defined by equation (3). TIFF2026076950000004.tif6150

[0039] Next, we will explain in detail the calculation of the balance between the pressure P2 generated on the liquid surface formed as the excess adhesive from the bonding region between the first substrate 1 and the second substrate 2, and the surface tension, using Figure 4. Note that pressure P2 refers to the pressure generated on the liquid surface at the end face of the adhesive in contact with the flow path when adhesive overflows from the bonding region between the first substrate 1 and the second substrate 2 after the process of forming the bonding region and before the process of curing the adhesive.

[0040] If we denote the surface tension of the adhesive that protrudes from the edge of the first substrate 1 as γ, this surface tension γ acts on the first substrate 1 and the second substrate 2 at contact angles θ1 and θ2, respectively. The surface tension at the contact line can be decomposed into components in the X and Z directions as shown below, and is expressed by equations (4) and (5). TIFF2026076950000005.tif6150TIFF2026076950000006.tif6150

[0041] In other words, the surface tension at the contact line is the sum of the value calculated by equation (4) and the value calculated by equation (5), and is shown by equation (6). TIFF2026076950000007.tif6150

[0042] In contrast, the resultant force P2 of the pressure generated on the liquid surface formed by the overflow is defined by equation (7), where L1 is the overflow length to the first substrate 1 and L2 is the overflow length to the second substrate 2, and the length of the liquid surface in the Z direction is approximately (L1 + L2). TIFF2026076950000008.tif6150

[0043] The value calculated by equation (6) is equal to the value calculated by equation (7). Therefore, the pressure P2 generated by the adhesive overflow at the edge of the first substrate 1 at the joint surface between the first substrate 1 and the second substrate 2 is defined by equation (8). TIFF2026076950000009.tif6150

[0044] Next, we will explain in detail the calculation of the balance between the pressure generated with respect to the liquid surface of the adhesive in the first recess 4 within the bonding region between the first substrate and the second substrate, and the surface tension, using Figure 5.

[0045] As shown in Figures 5(a) to 5(c), the first recess 4 is formed to have a width d1 in the X direction and a width d2 in the Y direction. Although Figures 5(a) and 5(b) show an example in which the first recess 4 is formed on the first substrate 1, it is not limited to this, and may be formed on the second substrate 2, for example. Furthermore, the planar shape of the recess (the shape horizontal to the bonding surface) may be an ellipse or a polygon in addition to a rectangle.

[0046] If the surface tension of the adhesive is γ, then, for example, if a first recess 4 is formed in the first substrate 1, this surface tension γ acts on the first substrate 1 at a contact angle θ1. Therefore, the surface tension at the contact line is given by equation (9). TIFF2026076950000010.tif6150

[0047] In contrast, the resultant force P3 of the pressure generated on the liquid surface in the recess is approximated by the length of the liquid surface in the X direction ≈ d1 and the length of the liquid surface in the Y direction ≈ d2, and is defined by equation (10). TIFF2026076950000011.tif6150

[0048] The value calculated by equation (9) is equal to the value calculated by equation (10). Therefore, the pressure P3 generated in the recess within the bonding region between the first substrate 1 and the second substrate 2 is defined by equation (11) based on these equations. TIFF2026076950000012.tif6150

[0049] Here, it is generally preferable that the adhesive is sufficiently wet to the surface from the viewpoint of adhesive strength, and if necessary, the substrate is surface-modified by surface treatment or a thin film with a surface free energy close to that of the adhesive is deposited. Furthermore, by heating during or after bonding to promote the curing reaction of the adhesive, the cohesive energy of the adhesive molecules is reduced, and as a result the surface tension of the adhesive decreases, and the difference in surface tension at the contact line between the first substrate 1 and the second substrate 2 becomes smaller. For this reason, in this embodiment, θ≈θ1≈θ2 and L≈L1≈L2 are assumed. That is, P1 in equation (3) can be redefined by equation (12), P2 in equation (8) can be redefined by equation (13), and P3 in equation (11) can be redefined by equation (14). TIFF2026076950000013.tif6150TIFF2026076950000014.tif6150TIFF2026076950000015.tif6150

[0050] These are the pressures that arise relative to the liquid surface shape at the end face of the adhesive when it is in a liquid state. However, the liquid surface shape of the adhesive is maintained even after it has hardened. Since the liquid surface shape of the adhesive in equilibrium is the shape just before hardening, the pressures that arose at the liquid surface shape of the adhesive in its liquid state can be calculated retrospectively based on the shape after hardening.

[0051] By using these pressure values, the protrusion at the first opening 7 is controlled based on the size of the first recess 4. Specifically, as a preferable range of P3 in the present embodiment, a first recess 4 having an X-direction width d1 and a Y-direction width d2 is formed such that P1 ≧ P3 ≧ P2.

[0052] FIG. 6 is a schematic view when the adhesive 6 is transferred to the first substrate 1, and FIG. 7 is a schematic view when joining is performed such that the Z-direction distance between the first substrate 1 and the second substrate 2 becomes H from the state shown in FIG. 6. At this time, as shown in FIG. 7, the adhesive 6 largely protrudes into an opening (first opening 7) formed by at least the end face of the first substrate and the second substrate. Since the adhesive 6 is at least in a state having fluidity at this time, the adhesive 6 is drawn into the first recess 4 by the pressure P3 generated by the formation of the liquid surface of the adhesive 6 in the first recess 4 provided in the first substrate 1.

[0053] In the process of drawing the adhesive 6 into the recess such as the first recess 4, it flows until the pressure P1 or the pressure P2 generated by the liquid surface shape of the adhesive 6 and the pressure P3 generated by the liquid surface shape in the recess become equal (see FIG. 11). For example, it flows until it becomes a shape as shown in FIGS. 8 and 9.

[0054] If the pressure P3 is large, even when the internal pressure of the recess increases due to outgas or the like generated during the curing process of the adhesive in the recess, it has a surface tension stronger than the increased internal pressure, so it is possible to prevent the adhesive from flowing out of the recess, which is preferable. However, if the pressure P3 is too large, specifically, if P1 < P3, the pressure P3 generated by the liquid surface shape of the recess is larger than the pressure P1 generated by the liquid surface shape at the opening end, so the adhesive continues to be drawn into the recess, and the end of the adhesive continues to retreat from the opening. As a result, for example, with respect to the end of the first substrate 1 as shown in FIG. 10, the end of the adhesive 6 largely retreats and a void is formed, and then it cures. Therefore, it is necessary to form the first recess 4 such that at least P1 ≧ P3.

[0055] The pressure P1 generated at the liquid surface of the adhesive 6 shown in Figure 9 is defined by equation (12). Regarding the distance H between the first substrate 1 and the second substrate 2 at the end of the adhesive bonding surface (the Z-direction length of the bonding surface, also called the substrate distance), if H is small (short), the flow resistance increases during the flow of the adhesive, making it difficult for the adhesive to flow. In addition, it is preferable to secure a certain length of H in order to fill in the steps caused by wiring and suppress voids during bonding, and specifically, H = 1.5 μm or more is preferable. Furthermore, if the substrate distance becomes long, the adhesive is more likely to move due to the influence of outgassing generated from the adhesive that has entered the recesses, so H is preferably 5.0 μm or less, and more preferably 4.0 μm or less.

[0056] Regarding the control of adhesive thickness, there are no particular limitations, but it is possible to control the thickness with relative precision by forming protrusions of a known height on the substrate or by mixing fillers of a known size into the adhesive.

[0057] Furthermore, the pressure P2 generated at the liquid surface where the adhesive 6 protrudes from the first substrate 1, as shown in Figure 8, is defined by equation (13). The protrusion width L is preferably relatively short, and specifically, it is preferably a single value within the range of 1.0H ≤ L ≤ 1.5H. In this embodiment, H = 1.5L. However, the most preferred value is H = 1.0L.

[0058] If the recesses set in this manner are formed, and P2 and P3 calculated from the shape after curing are P2 > P3, it is possible that the curing reaction of the adhesive proceeds before reaching equilibrium, reducing fluidity and making it impossible to control the amount of overflow to the desired level.

[0059] For the reasons explained above, in this embodiment, the preferred range for the pressures P1 to P3 generated at the liquid surface of the adhesive 6 in the first opening 7, the first recess 4, and the end of the first substrate 1 and the second substrate 2 is P1 ≥ P3 ≥ P2. Figure 11 shows this range.

[0060] Furthermore, Table 1 shows the difference between P1 and P2 (P1-P2) calculated from the substrate distance H in this case, and the adhesive overflow length L when L=1.0H and when L=1.5H, respectively. Table 1 shows that as the value of the substrate distance H increases, the difference between P1 and P2 decreases, and the range of selectable P3 decreases. In other words, as this indicates that the degree of freedom of the recess shape decreases, it is preferable that H be 5.0 μm or less so that the difference between P2 and P1 can be secured at around 5000 Pa, and more preferably 4.0 μm or less so that the difference between P2 and P1 can be secured at around 6000 Pa. [Table 1]

[0061] Here, in the region from P2 to P1 (the region indicated by the points in Figure 11), when the adhesive 6 is drawn into the first recess 4, the shape is maintained by the pressure P1 generated against the liquid surface formed as the end face of the adhesive at the edge of the first substrate 1, resulting in the shape shown in Figure 8. On the other hand, if the pressure P3 generated in the recess during the process of the adhesive being drawn into the recess or during the curing of the adhesive exceeds the pressure P1 generated against the liquid surface formed as the end face of the adhesive on the substrate 1, the shape will transition to the shape shown in Figure 9.

[0062] Therefore, the shape that satisfies P1≧P3≧P2 as the range of P3 in this embodiment includes the shape that extends beyond the range enclosed by P1 and P2 as shown in Figure 11. For example, the shape shown in Figure 12 is also included. Furthermore, for example, the shape in which the etching shape of the first substrate 1 is different, as shown in Figure 13, is also included.

[0063] Furthermore, since the recessed areas become non-transferable areas for adhesive when adhesive is transferred, the effect of reducing the amount of adhesive beforehand can also be expected. For this reason, in addition to the first recessed area 4 provided in addition to the opening for the ink flow path and the piezoelectric element housing, one or more second recessed areas 5 may be provided, each having a width in the X direction and a width in the Y direction that differs from that of the first recessed area 4. In that case, the effects of this embodiment can be obtained by forming recessed areas such that, when the greatest pressure among the pressures generated by the liquid surface shape formed in the first recessed area 4 and the liquid surface shape formed in the second recessed area 5 is P4, P1 ≥ P4 ≥ P2. In this embodiment, there are two types of recessed areas, the first recessed area 4 and the second recessed area 5, but there may be three or more types. Also, the planar shapes (cross-sectional shapes in the X and Y directions) of the first recessed area 4 and the second recessed area 5 may be different.

[0064] If the distance between the first recess 4 and the first opening 7 is large, there is a risk that the fluid (liquid adhesive) may have a significant effect on the walls of the first substrate 1 and the second substrate 2 due to friction during the flow of the adhesive. Therefore, it is preferable that the distance between the first recess 4 and the first opening 7 be small, and in this embodiment, it is preferable to position the first recess 4 at a distance of 100 μm or less from the first opening 7.

[0065] The position of the first recess 4 is not particularly limited. For example, as shown in Figure 2 or Figure 14, it can be positioned between the first opening 7 and the second opening 8 (closed space) for housing the piezoelectric actuator. Also, in Figure 2, it can be positioned between the first opening 7 connected to the pressure chamber 12 corresponding to the shown piezoelectric actuator and the first opening (not shown) connected to the pressure chamber (not shown) corresponding to a different piezoelectric actuator (not shown).

[0066] As shown in Figure 14, the first recess 4 in this embodiment is positioned. With this arrangement, after the adhesive 6 has flowed, the pressure P3 generated at the liquid surface of the adhesive 6 in the first recess 4 and the pressure generated at the liquid surface of the adhesive in the first opening 7 become equal in a steady state. At this time, the pressure P3 and the pressure generated at the liquid surface of the adhesive in the second opening 8 for housing the piezoelectric actuator also become equal in a steady state.

[0067] For example, as shown in Figure 15, the distance between substrates (the length in the Z direction of the bonding surface) may be different on the side closer to the first opening 7 and the side closer to the second opening 8 (H1, H2 in the figure). By increasing the distance between substrates H1 on the side closer to the first opening 7, it is possible to reduce the amount of adhesive that overflows. Also, in a closed space such as the second opening 8, there is a risk that the adhesive may be pushed out and a void may be created due to the increase in internal pressure caused by outgassing of the adhesive. Therefore, it is preferable to shorten the distance between substrates H2 on the side closer to the second opening 8. Shortening the distance between substrates H2 increases the pressure P1 generated at the liquid surface of the adhesive in the second opening 8, which makes it possible to suppress the formation of the void described above.

[0068] Furthermore, the first openings 7 may be arranged in multiple locations within the substrate at different sizes, and the distance between substrates on the side closest to each opening may be varied according to the size of each first opening 7 in the XY plane.

[0069] Here, from the aforementioned relationship P1≧P3≧P2, we can derive the relationship 2γcosθ / H≧2γcosθ(d1+d2) / d1d2≧γ(cosθ-sinθ) / L. Rearranging this relationship using the relationship L=H, which is the most preferred form of this embodiment, we can derive the relationship 1≧H(d1+d2) / d1d2≧(cosθ-sinθ) / 2cosθ.

[0070] From the viewpoint of adhesive wettability, it is preferable to set the widths d1 and d2 of the recesses relative to the distance H between the substrates at the open end such that θ≦35° and 1≧H(d1+d2) / d1d2≧0.15 (in other words, 1≧H(1 / d1+1 / d2)≧0.15). Furthermore, it is even more preferable to set the widths d1 and d2 of the recesses relative to the distance H between the substrates at the open end such that θ≦30° and 1≧H(d1+d2) / d1d2≧0.21 (in other words, 1≧H(1 / d1+1 / d2)≧0.21). In this case, it is preferable that H = 1.5 μm or more and 4.0 μm or less.

[0071] For example, when H=3.0, d1=10μm, and d2=10μm, H(d1+d2) / d1d2=0.6, which satisfies the aforementioned relationship, resulting in the width of the recess and the distance between substrates, making it possible to control the overflow of adhesive.

[0072] Up to this point, we have described the case where the planar shape of the recess is rectangular, as shown in Figure 5(c). However, this embodiment is also applicable when the planar shape is not rectangular. If the contact line of the wall surface of a recess with an arbitrary planar shape is γcosθ, the entire circumference of the recess is D, and the area of ​​the planar shape is S, then the force F acting on the entire circumference can be expressed as F = Dγcosθ. Therefore, since P = F / S, the pressure P3 acting on the meniscus of the recess in a planar shape within the range in which the effects of this disclosure can be obtained may be approximated and calculated as P3 ≈ Dγcosθ / S.

[0073] Here, from the aforementioned relationship P1≧P3≧P2, we can derive the relationship 2γcosθ / H≧Dγcosθ / S≧γ(cosθ-sinθ) / L. Rearranging this relationship using the relationship L=H, which is the most preferred form of this embodiment, we can derive the relationship 1≧HD / 2S≧(cosθ-sinθ) / 2cosθ.

[0074] From the viewpoint of adhesive wettability, it is preferable to set the planar shape of the recess relative to the substrate distance H at the open end such that θ ≤ 35° and 1 ≥ HD / 2S ≥ 0.15. Furthermore, it is more preferable to set the shape of the recess relative to the substrate distance H at the open end such that θ ≤ 30° and 1 ≥ HD / 2S ≥ 0.21. In this case, it is preferable that H = 1.5 μm or more and 4.0 μm or less.

[0075] Here are some calculation examples for typical planar shapes. When the planar shape is rectangular, as in Figure 5(c), or polygonal, the adhesive is more easily transmitted at the corners. For example, Figure 21(a) illustrates the corner of a rectangular shape as an example; the transmission of adhesive 6 to the corner promotes the introduction of the adhesive into the recess.

[0076] TIFF2026076950000017.tif30170

[0077] Figure 22 shows an example of such a polygon: a hexagon. Note that the polygon is not limited to this. Also, the n-sided polygon can be a regular n-sided polygon.

[0078] TIFF2026076950000018.tif43160

[0079] For example, taking the hexagon shown in Figure 23 as an example, H=2.0μm, D=24μm, S=34.46μm 2 As a result, HD / 2S = 0.696, which satisfies the aforementioned relationship between the recess width and the distance between substrates, making it possible to control the excess adhesive.

[0080] Furthermore, in the case of a regular n-sided polygon with side length a, the aforementioned formula can be used, but when n≧4, the angle formed by the line connecting the center of the planar shape and adjacent vertices is 360 / n(°), so D=na and S=na² / 4tan(180 / n). Therefore, for P3, it can be shown as P3=4γcosθtan(180 / n) / a. Note that Figure 24 illustrates a regular pentagon as an example, but it is not limited to this.

[0081] From the viewpoint of the wettability of the adhesive, it is preferable to set the angle such that P1≧P3≧P2, θ≦35°, and 1≧HD / 2S≧0.15. Furthermore, from the above-mentioned equation, it is preferable to set the planar shape of the recess with respect to the substrate distance H at the open end such that 1≧2Htan(180 / n) / a≧0.15. Moreover, it is even more preferable to set the shape of the recess with respect to the substrate distance H at the open end such that θ≦30°, and similarly from the above-mentioned equation, 1≧2Htan(180 / n) / a≧0.21. In this case, it is preferable that H=1.5μm or more and 4.0μm or less.

[0082] For example, in the case of a regular pentagon as shown in Figure 24, where a = 6 μm, when H = 3.0 μm, 2Htan(180 / n) / a = 0.727, which satisfies the aforementioned relationship, resulting in the width of the recess and the distance between substrates, making it possible to control the overflow of adhesive.

[0083] Incidentally, in the case of rectangular shapes like those in Figure 5(c) or polygons like those in Figures 22 and 24, the shape of the corners may not be stable due to variations in the size of the planar shape, etching conditions, and process. Therefore, the shape can be more easily stabilized by making the planar shape a circle or ellipse without corners. Furthermore, the pressure P3 generated at the liquid surface of the adhesive in the recess of this disclosure is generated when the liquid surfaces of the adhesive 6 connect within the recess. If the liquid surfaces do not connect due to the amount of adhesive 6 or the dimensions of the recess, the effects of this disclosure cannot be obtained. For these reasons, it is conceivable to make the planar shape a circle or ellipse.

[0084] Here, Figure 21(b) shows the case where the planar shape is circular. As shown in Figure 21(b), the absence of corners eliminates the adhesive 6 that would otherwise flow along the corners as in Figure 21(a). Therefore, the adhesive 6 that flows in from the joint surface of the recess can easily spread to the bottom surface of the second substrate 2. In this way, by making the planar shape circular or elliptical, the liquid surface can be more easily connected within the recess, which can make it easier to obtain the effects of this disclosure.

[0085] The following are specific examples of cases where the planar shape is circular or elliptical.

[0086] When the planar shape is a circle with radius r as shown in Figure 25, D = 2πr and S = πr², so P3 = 2γcosθ / r. From the viewpoint of the wettability of the adhesive, it is preferable to set the angle such that P1 ≥ P3 ≥ P2, θ ≤ 35°, and 1 ≥ HD / 2S ≥ 0.15. Furthermore, from the above equation, it is preferable to set the planar shape of the recess with respect to the distance H between the substrates at the open end so that 1 ≥ H / r ≥ 0.15. Moreover, it is even more preferable to set the shape of the recess with respect to the distance H between the substrates at the open end so that θ ≤ 30°, and similarly from the above equation, 1 ≥ H / r ≥ 0.21. In this case, it is preferable that H = 1.5 μm or more and 4.0 μm or less.

[0087] For example, in the case of a circle with radius r=10μm as shown in Figure 25, when H=3.0μm, H / r=0.3, which satisfies the aforementioned relationship, resulting in the width of the recess and the distance between substrates, making it possible to control the overflow of adhesive.

[0088] TIFF2026076950000019.tif25150

[0089] TIFF2026076950000020.tif51150

[0090] TIFF2026076950000021.tif26150

[0091] Incidentally, when the planar shape of the recess is polygonal, the shape of the corners may be deformed due to the effects of etching, etc. For example, if the corners become rounded as shown in Figure 27(a), a virtual vertex may be created on the extension of one side and calculations may be performed. Also, if the circularity of the corner is even larger than in Figure 27(a), as shown in Figure 27(b), calculations may be performed by combining a circular shape and a rectangular shape. Furthermore, in cases where there are many polygonal corners, as shown in Figures 28(a) and 28(b), and the corners become close to a circular or elliptical shape due to the effects of etching, calculations may be performed by approximating them to a circular or elliptical shape. In such cases, some error may occur, so it is preferable to make the recess such that P3 can be set so that there is a sufficient difference in value from the set values ​​of P1 and P2. Specifically, for example, it is preferable that the difference between P1 and P3, or the difference between P2 and P3, is 1000 Pa or more.

[0092] An example of a method for manufacturing the bonded substrate in this embodiment is shown in Figures 17 to 19 with respect to the B-B' cross-section in Figure 16. The substrate processing process in the manufacturing of the bonded substrate is not particularly limited and can be carried out using general substrate processing processes.

[0093] For example, if the substrate is a silicon substrate, semiconductor manufacturing processes can be used. After forming a desired etching mask on the substrate surface, processing can be performed by carrying out Si dry etching. The etching mask can be formed, for example, by using a novolac-based photoresist, exposing and developing it, and then patterning it. Si dry etching can also be performed using an etching method known as the Bosch process, for example, by using SF6 gas in the etching step and C4F8 gas in the coating step. Furthermore, substrate thinning can also be performed as needed.

[0094] As shown in Figure 17(a), a first substrate 1 and a second substrate 2 are prepared, each having a first opening 7, a second opening 8, a first recess 4, and a second recess 5 formed thereon. These openings and recesses may be formed simultaneously or separately. In this example, only the first recess 4 is shown between the first opening 7 and the second opening 8, but the second recess 5 may be formed between them, or both the first recess 4 and the second recess 5 may be formed.

[0095] As shown in Figure 17(b), the adhesive 6 is formed on the first substrate 1 by transfer. At this time, the adhesive 6 is not transferred to the first recess 4 or the second recess 5 on the transfer surface.

[0096] Figure 18(a) is a schematic cross-sectional view when the first substrate 1 and the second substrate 2 on which the piezoelectric element 9 and wiring 10 are formed are bonded together. At this time, the adhesive 6 fills the first recess 4 and the second recess 5 in this embodiment. Subsequently, by allowing the adhesive 6 to flow sufficiently and then curing it, the excess adhesive can be controlled (suppressed), as shown in Figure 18(b).

[0097] As shown in Figure 18(c), the second substrate 2 is thinned. Subsequently, as shown in Figure 18(d), a pressure chamber 12 is formed at a position corresponding to the piezoelectric element 9. In this embodiment, as an example, the process of forming the pressure chamber 12 after bonding and thinning the second substrate 2 is given. However, the method is not limited to this, and the pressure chamber 12 may be formed after bonding the thinned second substrate 2, or the second substrate 2 with the pressure chamber 12 already formed may be bonded.

[0098] As shown in Figure 19(a), adhesive 6 is transferred to the second substrate 2 and bonded to the third substrate 3. Although Figure 19(a) does not show recesses in the second substrate 2 for accommodating excess adhesive, they may be formed as needed. The overflow control using recesses described in this embodiment is also applicable to the bonding of the second substrate 2 and the third substrate 3.

[0099] As shown in Figure 19(b), the third substrate 3 is thinned to form the discharge port 13. Here, as an example, the process of forming the discharge port 13 after joining and thinning the third substrate 3 is given, but the process is not limited to this. For example, the discharge port 13 may be formed after joining the thinned third substrate, or the discharge port 13 may be formed on the third substrate and then joined. In addition, as ink flow paths, a first flow path (first opening 7) connected to a first pressure chamber (pressure chamber 12) corresponding to the first actuator and a second flow path (not shown) connected to a second pressure chamber (not shown) corresponding to the second actuator may be formed on the first substrate 1. A recess is placed at an appropriate distance between the first flow path and the second flow path.

[0100] As the adhesive 6, a material with good wettability and high adhesion to the substrate is preferably used. Furthermore, an adhesive made of a material that contains few air bubbles is preferred, and in this embodiment in particular, an adhesive made of a low viscosity material that flows easily is preferred. Moreover, it is preferable that such an adhesive contains any resin selected from the group consisting of epoxy resin, acrylic resin, silicone resin, benzocyclobutene resin, polyamide resin, polyimide resin, and urethane resin.

[0101] Curing methods for adhesive 6 include thermosetting and UV delayed curing. If either substrate is UV transparent, the UV curing method can be used. The adhesive is applied by spin-coating the adhesive onto a dry film and transferring it to one of the substrates on the bonding surface. However, the adhesive application method is not limited to this; screen printing or, in the case of a photosensitive adhesive, photolithography may be used.

[0102] Regarding the curing of adhesive 6, it is preferable to allow sufficient time for it to remain in a fluid, viscous state before curing. Alternatively, if using a thermosetting resin, the time for it to remain fluid can be ensured by slowing down the heating process of the heating device.

[0103] In this embodiment, the thermosetting resin benzocyclobutene can be suitably used. Benzocyclobutene is easy to control because its viscosity changes with temperature, and there is a region where the viscosity is about 10 to 100 Poise during bonding and curing, which allows the capillary action in the first recess 4 to work effectively and facilitates the flow of adhesive into the second recess 5.

[0104] For curing, a general apparatus capable of baking under a vacuum of 10 Pa or less is used, and the adhesive is cured by raising the temperature to 250°C at a heating rate of 5°C / min and then holding it for 1 hour. The adhesive can be made to flow during the heating process, specifically by passing through the low-viscosity temperature range of 130-200°C. The conditions for curing the adhesive are not particularly limited and can be appropriately changed depending on the selected material. However, it is preferable to ensure sufficient flow time for the adhesive by slowing the heating rate or holding the temperature in the low-viscosity range.

[0105] Regarding the thickness of the adhesive, it is preferable to form it thickly in order to eliminate voids (air bubbles) during bonding. It is preferable to form an adhesive layer before bonding that is at least 1.2 times, more preferably 1.5 times, the maximum distance between the first substrate 1 and the second substrate 2 after bonding. Note that while increasing the thickness of the adhesive can suppress voids, it makes it easier for the adhesive to overflow from the openings of each bonding surface.

[0106] <Examples> The following describes an example of a bonded substrate manufactured according to the method in the embodiment described above. The substrate processing process is not particularly limited and can be carried out using a general substrate processing process.

[0107] Furthermore, the surface tension in this disclosure was calculated using a value of 0.02 N / m. In addition, the contact angle between the liquid adhesive and the solid during its flow before curing was determined to be the same as the angle between the solid adhesive and the substrate, which can be confirmed from the cross-sectional shape after curing. Specifically, the contact angle was set to 15° for the calculation.

[0108] Table 2 shows the values ​​of each parameter in each embodiment. Specifically, it shows the relationship between the distance between the first and second substrates (length in the Z direction of the bonding surface) H, the width d1 in the X direction and d2 in the Y direction of the recess, the pressures P1 to P3 calculated from these values, and the overhang length L in the cross-sectional shape after curing. Note that in Table 2, the overhang length is referred to as the overhang amount.

[0109] [Table 2]

[0110] Table 3 shows the parameter values ​​for each planar shape in each embodiment. Specifically, it shows the relationship between the inter-substrate distance (Z-direction length of the bonding surface) H between the first and second substrates, the total circumference D calculated from the shape parameters of the planar shape, the area S, the pressures P1 to P3 calculated from these values, and the overhang length L in the cross-sectional shape after curing. Note that in Table 3, the overhang length is referred to as the overhang amount.

[0111] [Table 3]

[0112] Benzocyclobutene, a thermosetting resin, was used as the adhesive, and the first and second substrates were bonded together by heating to 130°C under a vacuum of 10 Pa. Subsequently, the adhesive was cured by holding it at 150°C for 30 minutes under a vacuum of 10 Pa, then increasing the temperature by 5°C / min to reach 250°C and holding it for 1 hour. Finally, after forming the discharge port, the amount and shape of adhesive overflow were checked in the cross section to confirm whether the effects of this disclosure were achieved.

[0113] [First Embodiment] When joining the first substrate and the second substrate with a thickness of H=2.0μm, recesses of d1=10μm and d2=10μm were placed. A liquid ejection head using this bonded substrate was fixed in place, and single-color printing was performed while transporting the recording medium, and it was confirmed that printing could be performed without any problems. When the liquid ejection head was actually disassembled and checked, it was found that in this embodiment, the final overflow length L was L<2.0μm, confirming that the effect of this embodiment was achieved.

[0114] [Second Example] When joining the first substrate and the second substrate with a thickness of H=4.0μm, recesses of d1=10μm and d2=50μm were placed. A liquid ejection head using this bonded substrate was fixed in place, and single-color printing was performed while transporting the recording medium, and it was confirmed that printing could be performed without any problems. When the liquid ejection head was actually disassembled and checked, it was found that in this embodiment, the final overflow length L was L<4.0μm, confirming that the effect of this embodiment was achieved.

[0115] [Third Embodiment] When joining the first substrate and the second substrate with a gap of H=3.0μm, a first recess with d1=10μm and d2=10μm, and a second recess with d1=30μm and d2=30μm were arranged. A liquid ejection head using this bonded substrate was fixed, and monochrome printing was performed while transporting the recording medium, and it was confirmed that printing could be performed without problems. When the liquid ejection head was actually disassembled and checked, it was found that in this embodiment, the final overflow length L was L<3.0μm, confirming that the effect of this embodiment was achieved.

[0116] [Comparative Example 1] When joining the first and second substrates with a thickness of H=2.0μm, recesses of d1=30μm and d2=50μm were placed. When a liquid ejection head using this bonded substrate was fixed and monochrome printing was performed while transporting the recording medium, streaks (areas where printing was not performed) occurred. Upon actually disassembling the liquid ejection head and checking, it was confirmed that in this comparative example, the final overflow length L was L>3.0μm, and that there were areas where the overflowed adhesive had entered the flow path of the bonded surface. In other words, the effect of this embodiment was not obtained.

[0117] [Comparative Example 2] When joining the first and second substrates with a thickness of H=6.0μm, recesses of d1=10μm and d2=10μm were placed. When a liquid ejection head using this bonded substrate was fixed and monochrome printing was performed while transporting the recording medium, streaks (areas that were not printed) occurred. When the liquid ejection head was actually disassembled to check the final overflow length, it was confirmed that in this comparative example, adhesive was being drawn in from the edge of the substrate as shown in Figure 10, and it was highly likely that bubbles were accumulating in the gap of the bonded surface. In other words, the effect of this embodiment was not obtained.

[0118] [Fourth embodiment] When joining the first and second substrates with a thickness of H=2.5μm, a regular octagonal recess with a planar shape of a=3μm was placed. A liquid ejection head using this bonded substrate was fixed in place, and monochrome printing was performed while transporting the recording medium, and it was confirmed that printing could be performed without any problems. When the liquid ejection head was actually disassembled and checked, it was found that in this embodiment, the final overflow length L was L<2.5μm, confirming that the effect of this embodiment was achieved.

[0119] [Fifth Example] When joining the first substrate and the second substrate with a thickness of H=1.5μm, a hexagonal recess, as shown in Figure 28, was positioned. A liquid ejection head using this bonded substrate was fixed in place, and monochrome printing was performed while transporting the recording medium. It was confirmed that printing could be performed without any problems. Upon actually disassembling the liquid ejection head, it was found that in this embodiment, the final overflow length L was L<1.5μm, confirming that the effect of this embodiment was achieved.

[0120] [Sixth Example] When joining the first substrate and the second substrate with a thickness of H=2.5μm, a hexagonal recess, as shown in Figure 23, was positioned. A liquid ejection head using this bonded substrate was fixed in place, and single-color printing was performed while transporting the recording medium. It was confirmed that printing could be performed without any problems. Upon actually disassembling the liquid ejection head, it was found that in this embodiment, the final overflow length L was L<2.5μm, confirming that the effect of this embodiment was achieved.

[0121] [Seventh Example] When joining the first and second substrates with a thickness of H=3.0μm, a regular dodecagonal recess with a planar shape of a=3 was placed. Furthermore, due to concerns about the effect of etching on the corners, calculations were also attempted using a circle with a radius of r=5.8μm, but it was confirmed that the calculated values ​​did not change significantly. A liquid ejection head using this bonded substrate was fixed, and single-color printing was performed while transporting the recording medium, and it was confirmed that printing could be performed without problems. When the liquid ejection head was actually disassembled and checked, it was found that in this embodiment, the final overflow length L was L<3.0μm, confirming that the effect of this embodiment was achieved.

[0122] [Eighth Example] When joining the first and second substrates with a thickness of H=2.5μm, a circular recess with a planar shape of r=4μm was placed. A liquid ejection head using this bonded substrate was fixed in place, and single-color printing was performed while transporting the recording medium, and it was confirmed that printing could be performed without any problems. When the liquid ejection head was actually disassembled and checked, it was found that in this embodiment, the final overflow length L was L<2.5μm, confirming that the effect of this embodiment was achieved.

[0123] [Ninth Example] When joining the first and second substrates with a thickness of H=5.0μm, a circular recess with a planar shape of r=6μm was placed. A liquid ejection head using this bonded substrate was fixed in place, and single-color printing was performed while transporting the recording medium, and it was confirmed that printing could be performed without any problems. When the liquid ejection head was actually disassembled and checked, it was found that in this embodiment, the final overflow length L was L<5.0μm, confirming that the effect of this embodiment was achieved.

[0124] [Tenth embodiment] When joining the first substrate and the second substrate with a thickness of H=2.0μm, an elliptical recess with a planar shape of a=10μm and b=2.5μm was placed. A liquid ejection head using this bonded substrate was fixed in place, and monochrome printing was performed while transporting the recording medium, and it was confirmed that printing could be performed without any problems. When the liquid ejection head was actually disassembled and checked, it was found that in this embodiment, the final overflow length L was L<2.0μm, confirming that the effect of this embodiment was achieved.

[0125] [Embodiment 11] When joining the first substrate and the second substrate with a thickness of H=4.0μm, an elliptical recess with a planar shape of a=15μm and b=5μm was placed. A liquid ejection head using this bonded substrate was fixed in place, and single-color printing was performed while transporting the recording medium, and it was confirmed that printing could be performed without any problems. When the liquid ejection head was actually disassembled and checked, it was found that in this embodiment, the final overflow length L was L<4.0μm, confirming that the effect of this embodiment was achieved.

[0126] [Twelfth Example] When joining the first and second substrates with a thickness of H=3.0μm, a first circular recess with a planar shape of r=4μm and a second elliptical recess with a=15μm and b=10μm were arranged. A liquid ejection head using this bonded substrate was fixed in place, and monochrome printing was performed while transporting the recording medium, and it was confirmed that printing could be performed without any problems. When the liquid ejection head was actually disassembled and checked, it was found that in this embodiment, the final overflow length L was L<3.0μm, confirming that the effect of this embodiment was achieved.

[0127] [Third Comparative Example] When joining the first and second substrates with a thickness of H=2.5μm, a hexagonal recess, as shown in Figure 29, was placed. When a liquid ejection head using this bonded substrate was fixed and monochrome printing was performed while transporting the recording medium, streaks (areas that were not printed) were observed. When the liquid ejection head was actually disassembled to check the final overflow length, it was confirmed that in this comparative example, adhesive was being drawn in from the edge of the substrate as shown in Figure 10, and it was highly likely that bubbles were accumulating in the gap of the bonded surface. In other words, the effect of this embodiment was not obtained.

[0128] [Comparative Example 4] When joining the first and second substrates with a thickness of H=1.5μm, a circular recess with a planar shape of r=15μm was placed. When a liquid ejection head using this bonded substrate was fixed and monochrome printing was performed while transporting the recording medium, streaks (areas where printing was not performed) occurred. Upon actually disassembling the liquid ejection head and checking, it was confirmed that in this comparative example, the final overflow length L was L>1.5μm, and that there were areas where the overflowed adhesive had entered the flow path of the bonded surface. In other words, the effect of this embodiment was not obtained.

[0129] [Comparative Example #5] When joining the first and second substrates with a thickness of H=5.0μm, an elliptical recess with a planar shape of a=10μm and b=2.5μm was placed. When a liquid ejection head using this bonded substrate was fixed and monochrome printing was performed while transporting the recording medium, streaks (areas that were not printed) occurred. When the liquid ejection head was actually disassembled to check the final overflow length, it was confirmed that in this comparative example, there was a high possibility that bubbles were accumulating in the gap of the bonded surface. In other words, adhesive was being drawn in from the edge of the substrate as shown in Figure 10, and the effect of this embodiment was not obtained.

[0130] <Examples of application of the above embodiment> The following describes an example of the application of the bonded substrate in the above-described embodiment, using Figure 20. Figure 20 shows an example of a liquid ejection device having a liquid ejection head manufactured using the bonded substrate shown in the above-described embodiment. Here, as an example, an inkjet recording device (hereinafter referred to as the recording device) 1000 that ejects ink for recording will be described.

[0131] The recording device 1000 is a line-type recording device having a transport unit 1100 for transporting the recording medium 200 and a line-type liquid discharge head 300 arranged substantially perpendicular to the transport direction of the recording medium 200. The recording device 1000 performs recording while transporting the recording medium 200.

[0132] The liquid ejection head 300 includes a negative pressure control unit 301 that controls the negative pressure in the circulation path, a liquid supply unit 302 that is in fluid communication with the negative pressure control unit 301, a liquid connection part 304 that serves as a liquid supply port and discharge port for the liquid supply unit 302, and a housing 305. The liquid ejection head 300 is capable of full-color recording using cyan C, magenta M, yellow Y, and black K inks. A supply channel for supplying ink to the liquid ejection head 300, as well as a main tank and buffer tank as liquid supply means, are connected to the liquid ejection head 300 in a way that allows ink to flow. In addition, an electrical control unit that transmits power and ejection control signals to the liquid ejection head 300 is electrically connected to the liquid ejection head 300.

[0133] <Effects of this embodiment> Conventionally, during the manufacturing of liquid ejection heads, if a large amount of adhesive protruded into the area housing energy generating elements such as piezoelectric elements, it could potentially affect the operation of those elements. In particular, when the opening that forms the ink flow path was small, blockage by the adhesive was more likely to occur, leading to problems such as the inability to eject ink.

[0134] This problem becomes particularly noticeable when a sufficient amount of adhesive is needed to fill in the step caused by wiring on the bonding surface, or when a sufficient amount of adhesive is needed due to a long Z-direction distance between the bonding surfaces, i.e., the distance between substrates, and variations occur in the application or transfer of the adhesive. To address this issue, a conventional method has been implemented of providing a large recess capable of containing adhesive around the opening that serves as the ink flow path. However, simply providing such a large recess was not always sufficient to control the occurrence of this problem.

[0135] Therefore, in this embodiment, a bonded substrate 80 is manufactured by the method described above, and a liquid discharge head is manufactured using the manufactured bonded substrate 80. In the manufacturing method of this embodiment, when bonding substrates having openings that will become ink channels and openings that will house piezoelectric elements via adhesive, recesses are arranged such that the pressure generated at the liquid surface of the adhesive satisfies the predetermined conditions described above.

[0136] There are three types of pressure here. Specifically, there is the pressure P3 generated at the liquid surface of the adhesive in the recess where the adhesive is drawn in. There is also the pressure P1 generated at the liquid surface of the adhesive at the end face in the bonding region between the first and second substrates. Furthermore, there is the pressure P2 generated at the liquid surface of the adhesive at the end face when the adhesive spills out from the bonding region. It is desirable that when the length of the adhesive spillage in the X direction is L, and the distance between the substrates is H, L = 1.5H.

[0137] In this embodiment, recesses having a width that allows for capillary action to draw in P1 ≥ P3 ≥ P2 are appropriately arranged on the substrate. This makes it possible to control (suppress) adhesive leakage into the openings that house the energy generating elements and the openings that serve as ink channels, thereby enabling the manufacture of a stable bonded substrate. Consequently, by using this bonded substrate, a stable liquid dispensing head can be manufactured.

[0138] [Technical Features of This Disclosure] This disclosure includes the following components:

[0139] (Configuration 1) A method for manufacturing a liquid discharge head in which a first substrate and a second substrate are joined via an adhesive, comprising the steps of: preparing a first substrate and a second substrate, each having a first opening that serves as a liquid flow path and a recess that accommodates a portion of the adhesive formed in at least one of them; joining the first substrate and the second substrate via an adhesive to form a bonding region between the first substrate and the second substrate by the adhesive; and curing the adhesive, wherein the width of the recess in the short direction of the first substrate and the width of the recess in the long direction of the first substrate are compared with respect to the first substrate in the stacking direction of the first substrate and the second substrate. A method for manufacturing a liquid discharge head, characterized in that, when the distance between the second substrate and the liquid discharge head is H, and after the step of forming the bonding region and before the curing step, P1 is the pressure generated on the liquid surface as the end face of the adhesive in contact with the flow channel within the bonding region when the adhesive does not protrude from the bonding region, P2 is the pressure generated on the liquid surface as the end face of the adhesive in contact with the flow channel within the range satisfying 1.0H ≤ L ≤ 1.5H when the adhesive protrudes from the bonding region, and P3 is the pressure generated on the liquid surface of the adhesive in the recess, P1 ≥ P3 ≥ P2. (Configuration 2) A method for manufacturing a liquid discharge head according to Configuration 1, characterized in that the position in the short-side direction of the end face in contact with the flow path on the first substrate is different from the position in the short-side direction of the end face in contact with the flow path on the second substrate. (Configuration 3) The method for manufacturing a liquid dispensing head according to Configuration 1 or 2, characterized in that the step of curing the adhesive is performed after the adhesive has reached an equilibrium state at the temperature in which it flows. (Configuration 4) A method for manufacturing a liquid dispensing head according to any one of Configurations 1 to 3, characterized in that the condition satisfies 1.5 μm ≤ H ≤ 5.0 μm. (Configuration 5) A method for manufacturing a liquid dispensing head according to any one of Configurations 1 to 4, characterized in that the condition satisfies 1.5 μm ≤ H ≤ 4.0 μm. (Configuration 6) A method for manufacturing a liquid dispensing head according to any one of Configurations 1 to 5, characterized in that the recess comprises one or more first recesses and second recesses which differ from the first recess in at least one of their widths in the short direction and the long direction, and when the largest pressure generated with respect to the liquid surface of the adhesive formed in each of the first recesses and the second recesses is denoted as P4, P1 ≥ P4 ≥ P2. (Configuration 7) A method for manufacturing a liquid discharge head according to any one of Configurations 1 to 6, characterized in that, in the bonding region, a second opening for arranging a piezoelectric element is formed in at least one of the first substrate and the second substrate, the piezoelectric element constitutes an actuator, and the recess is arranged between the second opening and the first opening which becomes the flow path. (Configuration 8) A method for manufacturing a liquid discharge head according to any one of Configurations 1 to 7, characterized in that the distance between substrates in the bonding region is different on the first opening side and the second opening side. (Configuration 9) A method for manufacturing a liquid discharge head according to any one of Configurations 1 to 8, characterized in that the flow path includes a first flow path connected to a first pressure chamber corresponding to a first actuator and a second flow path connected to a second pressure chamber corresponding to a second actuator, and in the joining region, the recess is located between the first flow path and the second flow path. (Configuration 10) A method for manufacturing a liquid dispensing head according to any one of Configurations 1 to 9, characterized in that a plurality of openings of different sizes are arranged as the first opening. (Configuration 11) A method for manufacturing a liquid dispensing head according to any one of Configurations 1 to 10, characterized in that the distance in the stacking direction between the first substrate and the second substrate for each of the plurality of openings is different depending on the different sizes of the first opening. (Configuration 12) A liquid discharge head comprising a first substrate and a second substrate joined to the first substrate via an adhesive, wherein at least one of the first substrate and the second substrate has an opening that serves as a flow path and a recess formed therein, characterized in that when the width of the recess in the short direction of the first substrate is d1, the width of the recess in the longitudinal direction of the first substrate is d2, and the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate is H, the condition 1≧H(1 / d1+1 / d2)≧0.15 is satisfied. (Configuration 13) A liquid discharge head according to Configuration 12, characterized in that 1 ≥ H(1 / d1 + 1 / d2) ≥ 0.21. (Configuration 14) A liquid dispensing head having a first substrate and a second substrate joined to the first substrate via an adhesive, wherein at least one of the first substrate and the second substrate has an opening that serves as a flow path and a recess formed in the liquid dispensing head, and the liquid dispensing device satisfies 1≧H(1 / d1+1 / d2)≧0.15 when the width of the recess in the short direction of the first substrate is d1, the width of the recess in the longitudinal direction of the first substrate is d2, and the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate is H. (Configuration 15) A liquid dispensing device according to Configuration 14, characterized in that 1 ≥ H(1 / d1 + 1 / d2) ≥ 0.21. (Configuration 16) A liquid discharge head comprising a first substrate and a second substrate joined to the first substrate via an adhesive, wherein at least one of the first substrate and the second substrate has an opening that serves as a flow path and a recess formed therein, wherein when the entire circumference of a planar shape horizontal to the joining surface of the recess of the first substrate is D and the area of ​​the planar shape is S, and when the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate is H, the relationship 1 ≥ HD / 2S ≥ 0.15 is satisfied. (Configuration 17) A liquid discharge head according to Configuration 16, characterized in that 1 ≥ HD / 2S ≥ 0.21 is satisfied. (Configuration 18) The liquid dispensing head according to Configuration 16 or 17, characterized in that the planar shape horizontal to the bonding surface of the recess of the first substrate is a circle with radius r, and when the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate is H, the relationship 1 ≥ H / r ≥ 0.15 is satisfied. (Composition 19) TIFF2026076950000024.tif22150 (configuration 20) TIFF2026076950000025.tif31150 (configuration 21) TIFF2026076950000026.tif31150 (configuration 22) TIFF2026076950000027.tif34150 (configuration 23) TIFF2026076950000028.tif34150 (Configuration 24) A liquid discharge head according to any one of Configurations 16 to 23, characterized in that the planar shape horizontal to the bonding surface of the recess of the first substrate is a regular n-gon (n=4), the length of one side of the regular n-gon is a, the angle formed by the straight line connecting the center of the planar shape and an adjacent vertex is 360 / n (°), and when the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate is H, the condition 1≧2Htan(180 / n) / a≧0.15 is satisfied. (Configuration 25) A liquid discharge head according to any one of Configurations 16 to 24, characterized in that the planar shape horizontal to the bonding surface of the recess of the first substrate is a regular n-gon (n=4), the length of one side of the regular n-gon is a, the angle formed by the straight line connecting the center of the planar shape and an adjacent vertex is 360 / n(°), and when the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate is H, the condition 1≧2Htan(180 / n) / a≧0.21 is satisfied. (Configuration 26) A liquid dispensing device comprising a liquid dispensing head having a first substrate and a second substrate joined to the first substrate via an adhesive, wherein at least one of the first substrate and the second substrate has an opening that serves as a flow path and a recess formed therein, wherein when the entire circumference of the planar shape horizontal to the joining surface of the recess of the first substrate is D and the area of ​​the planar shape is S, and when the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate is H, the relationship 1 ≥ HD / 2S ≥ 0.15 is satisfied. (Configuration 27) A liquid dispensing device according to Configuration 26, characterized in that 1 ≥ HD / 2S ≥ 0.21 is satisfied. [Explanation of Symbols]

[0140] 1: First circuit board 2: Second substrate 4: First recess 7: First opening 101: Liquid dispensing head d1: X-direction width of the first recess d2: Y-direction width of the first recess

Claims

1. A method for manufacturing a liquid dispensing head in which a first substrate and a second substrate are joined together via an adhesive, The process involves preparing a first substrate and a second substrate, each having a first opening that serves as a liquid flow path and a recess that accommodates a portion of the adhesive, in at least one of them. A step of joining the first substrate and the second substrate via an adhesive to form a bonded area between the first substrate and the second substrate by the adhesive, The process of curing the adhesive, Includes, With respect to the width of the recess in the short direction of the first substrate and the width of the recess in the longitudinal direction of the first substrate, let H be the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate, and after the step of forming the bonding region and before the curing step, when the adhesive does not protrude from the bonding region, P1 is the pressure generated on the liquid surface as the end face of the adhesive in contact with the flow channel within the bonding region, and when the adhesive does protrude from the bonding region, let L be the length of the protruding adhesive, P2 is the pressure generated on the liquid surface as the end face of the adhesive in contact with the flow channel within the range that satisfies 1.0H ≤ L ≤ 1.5H, and P3 is the pressure generated on the liquid surface of the adhesive in the recess, such that P1 ≥ P3 ≥ P2. A method for manufacturing a liquid dispensing head, characterized by the following:

2. The position of the end face in contact with the flow path in the first substrate in the short-side direction is different from the position of the end face in contact with the flow path in the short-side direction in the second substrate. A method for manufacturing a liquid dispensing head according to feature 1.

3. The step of curing the adhesive is performed after the adhesive has reached an equilibrium state at the temperature in which it flows. The method for manufacturing a liquid dispensing head according to feature 2.

4. Satisfying 1.5 μm ≤ H ≤ 5.0 μm, The method for manufacturing a liquid dispensing head according to feature 3.

5. Satisfying 1.5 μm ≤ H ≤ 4.0 μm, The method for manufacturing a liquid dispensing head according to feature 4.

6. The recess comprises one or more recesses, including a first recess and a second recess that differs from the first recess in at least one of its widths in the short direction and the long direction. When P4 is the largest pressure generated with respect to the liquid surface of the adhesive formed in the first recess and the second recess, the following conditions are met: P1 ≥ P4 ≥ P2. The method for manufacturing a liquid dispensing head according to feature 5.

7. In the bonding region, a second opening for arranging a piezoelectric element is formed in at least one of the first substrate and the second substrate, the piezoelectric element constitutes an actuator, and the recess is arranged between the second opening and the first opening which forms the flow path. The method for manufacturing a liquid dispensing head according to feature 6.

8. The distance between the substrates in the bonding region is different on the first opening side and the second opening side. A method for manufacturing a liquid dispensing head according to feature 7.

9. The aforementioned flow path includes a first flow path connected to a first pressure chamber corresponding to a first actuator, and a second flow path connected to a second pressure chamber corresponding to a second actuator. In the joining region, the recess is located between the first flow path and the second flow path. The method for manufacturing a liquid dispensing head according to feature 8.

10. The first opening consists of multiple openings of different sizes. The method for manufacturing a liquid dispensing head according to feature 9.

11. Depending on the different sizes of the first opening, the distance between the first substrate and the second substrate in the stacking direction for each of the plurality of openings is different. A method for manufacturing a liquid dispensing head according to claim 10.

12. The first substrate and A second substrate is bonded to the first substrate via an adhesive, It has, A liquid discharge head having an opening that serves as a flow path and a recess formed in at least one of the first substrate and the second substrate, When the width of the recess in the short direction of the first substrate is d1, the width of the recess in the long direction of the first substrate is d2, and the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate is H, then 1 ≥ H(1 / d1 + 1 / d2) ≥ 0.15 is satisfied. A liquid dispensing head characterized by the following features.

13. Satisfying 1 ≥ H(1 / d1 + 1 / d2) ≥ 0.21, The liquid dispensing head according to feature 12.

14. A liquid dispensing head having a first substrate and a second substrate joined to the first substrate via an adhesive, wherein at least one of the first substrate and the second substrate has an opening that serves as a flow path and a recess formed therein, When the width of the recess in the short direction of the first substrate is d1, the width of the recess in the long direction of the first substrate is d2, and the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate is H, then 1 ≥ H(1 / d1 + 1 / d2) ≥ 0.15 is satisfied. A liquid dispensing device characterized by the following features.

15. Satisfying 1 ≥ H(1 / d1 + 1 / d2) ≥ 0.21, The liquid dispensing device according to feature 14.

16. The first substrate and A second substrate is bonded to the first substrate via an adhesive, It has, A liquid discharge head having an opening that serves as a flow path and a recess formed in at least one of the first substrate and the second substrate, If D is the entire circumference of the planar shape horizontal to the bonding surface of the recess of the first substrate, and S is the area of ​​the planar shape, then H is the distance between the first substrate and the second substrate in the stacking direction between the first substrate and the second substrate, and the following conditions satisfy 1 ≥ HD / 2S ≥ 0.

15. A liquid dispensing head characterized by the following features.

17. Satisfying 1 ≥ HD / 2S ≥ 0.21, The liquid dispensing head according to feature 16.

18. The planar shape of the recess of the first substrate is a circle with radius r, When H is the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate, the following conditions satisfy 1 ≥ H / r ≥ 0.

15. The liquid dispensing head according to feature 16.

19. The planar shape of the recess of the first substrate is a circle with radius r, When H is the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate, the following conditions satisfy 1 ≥ H / r ≥ 0.

21. The liquid dispensing head according to feature 16.

20.

21.

22.

23.

24. The planar shape of the first substrate horizontal to the bonding surface of the recess is a regular n-gon (n=4), Let a be the length of one side of the regular n-gon, let 360 / n (°) be the angle formed by the straight line connecting the center of the planar shape to an adjacent vertex, and let H be the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate, then satisfy 1 ≥ 2H tan(180 / n) / a ≥ 0.

15. The liquid dispensing head according to feature 16.

25. The planar shape of the first substrate horizontal to the bonding surface of the recess is a regular n-gon (n=4), Let a be the length of one side of the regular n-gon, let 360 / n (°) be the angle formed by the straight line connecting the center of the planar shape to an adjacent vertex, and let H be the distance between the first substrate and the second substrate in the stacking direction of the first substrate and the second substrate, then satisfy 1 ≥ 2H tan(180 / n) / a ≥ 0.

21. The liquid dispensing head according to feature 16.

26. The first substrate and A second substrate is bonded to the first substrate via an adhesive, It has, A liquid dispensing device comprising a liquid dispensing head having an opening that serves as a flow path and a recess formed in at least one of the first substrate and the second substrate, If D is the entire circumference of the planar shape horizontal to the bonding surface of the recess of the first substrate, and S is the area of ​​the planar shape, then H is the distance between the first substrate and the second substrate in the stacking direction between the first substrate and the second substrate, and the following conditions satisfy 1 ≥ HD / 2S ≥ 0.

15. A liquid dispensing device characterized by the following features.

27. Satisfying 1 ≥ HD / 2S ≥ 0.21, The liquid dispensing device according to feature 26.

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